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-   -   3 blade Max prop vs 3 blade fixed? (http://www.cruisersforum.com/forums/f47/3-blade-max-prop-vs-3-blade-fixed-171368.html)

Davidhoy 19-08-2016 20:54

3 blade Max prop vs 3 blade fixed?
 
I recently bought a Morgan 462, which are known for their horrendous handling when backing down. The boat has a 3 blade fixed prop installed, but I found a 3 blade Max prop in one of the storage compartments. It looks like it could use reconditioning, but otherwise seems ok. I did some reading, and Max props supposedly give you about 80% more power in reverse than a traditional fixed blade. If this is true, might switching to that prop help with my backing down handling issues? I'm not looking for a margin bullet that will suddenly make the boat a dream to handle in reverse, but rather something that will give me something, anything, better than what I have now with the fixed blade prop.

Regards,
David


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Steady Hand 20-08-2016 20:34

Re: 3 blade Max prop vs 3 blade fixed?
 
I would contact the previous owner and ask them why the Max Prop was not installed. :)

Davidhoy 20-08-2016 20:47

Re: 3 blade Max prop vs 3 blade fixed?
 
Quote:

Originally Posted by Steady Hand (Post 2193812)
I would contact the previous owner and ask them why the Max Prop was not installed. :)


The PO installed the fixed blade prop in place of the Max. He'd owned the boat just over two years, and I saw a copy of his pre-purchase survey that noted that the Max prop needed reconditioning. I suspect that he installed the fixed blade rather than do the reconditioning, probably due to cost.

I'm willing to recondition and reinstall the max prop if it will help with better handling when reversing. More power should make backing down easier, right? I don't really know the answer, hence my question...

Regards,
David


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JPA Cate 20-08-2016 21:05

Re: 3 blade Max prop vs 3 blade fixed?
 
Hi, Davidhoy,

I don't think even a new Maxi would give you 80% more thrust in reverse, compared to the 3 blade, but perhaps 80% of it's thrust. That said, while you're sailing, towing the 3 blade fixed prop around is like towing a bucket of *whatever* under sail. So the real question here is whether you could put up with a good performing Maxi Prop (after reconditioning) for the fuel economy and sailing performance it would gain.

Somebody, sometime, was convinced the MaxProp would be a good deal for the boat, and we've always used folders or featherers, and put up with the loss of thrust in reverse. There are skills involved in backing full keel or cutaway forefoot monohulls. Might a little extra knowledge about backing up help? There are some archived threads here about that (use the Google Special Search function, in the menu below the CF Search), that you could harvest some ideas from. And I bet there's probably some U Tube footage, as well.

If that fixed 3 blade was not carefully researched, the previous owner may have got the pitch wrong, if it was a hurried re-placement. If you decide you want to keep it, you might check at next haulout, usually they are stamped with the pitch and diameter is easy to measure.

Good luck with your project.

Ann

Steady Hand 20-08-2016 21:05

Re: 3 blade Max prop vs 3 blade fixed?
 
Quote:

Originally Posted by Davidhoy (Post 2193818)
The PO installed the fixed blade prop in place of the Max. He'd owned the boat just over two years, and I saw a copy of his pre-purchase survey that noted that the Max prop needed reconditioning. I suspect that he installed the fixed blade rather than do the reconditioning, probably due to cost.

I'm willing to recondition and reinstall the max prop if it will help with better handling when reversing. More power should make backing down easier, right? I don't really know the answer, hence my question...

Regards,
David


Sent from my iPad using Cruisers Sailing Forum

I see. I don't own a max prop. But from all the reading I have done about boats, the consensus among owners is that the Max Prop is a worthy improvement over a fixed. I don't know the cost of reconditioning one either. But, I would consider whatever cost that might be to be simply a "cost of ownership" and do it, then install it on place of the fixed prop. But again, I don't own one, so this is my opinion and intuition.

Good luck.

Steady Hand 20-08-2016 21:08

Re: 3 blade Max prop vs 3 blade fixed?
 
Quote:

Originally Posted by Ann T. Cate (Post 2193823)
Hi, Davidhoy,

I don't think even a new Maxi would give you 80% more thrust in reverse, compared to the 3 blade, but perhaps 80% of it's thrust. That said, while you're sailing, towing the 3 blade fixed prop around is like towing a bucket of *whatever* under sail. So the real question here is whether you could put up with a good performing Maxi Prop (after reconditioning) for the fuel economy and sailing performance it would gain.

Somebody, sometime, was convinced the MaxProp would be a good deal for the boat, and we've always used folders or featherers, and put up with the loss of thrust in reverse. There are skills involved in backing full keel or cutaway forefoot monohulls. Might a little extra knowledge about backing up help? There are some archived threads here about that (use the Google Special Search function, in the menu below the CF Search), that you could harvest some ideas from. And I bet there's probably some U Tube footage, as well.

If that fixed 3 blade was not carefully researched, the previous owner may have got the pitch wrong, if it was a hurried re-placement. If you decide you want to keep it, you might check at next haulout, usually they are stamped with the pitch and diameter is easy to measure.

Good luck with your project.

Ann

Good advice! :thumb:

Davidhoy 20-08-2016 21:13

Re: 3 blade Max prop vs 3 blade fixed?
 
Quote:

Originally Posted by Ann T. Cate (Post 2193823)
There are skills involved in backing full keel or cutaway forefoot monohulls. Might a little extra knowledge about backing up help?


Thanks, Ann! Very good point, one I'm working on already. Just trying not to embarrass myself too much in the process ;-)


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UNCIVILIZED 20-08-2016 21:27

Re: 3 blade Max prop vs 3 blade fixed?
 
I had a 2-bladed MaxProp on my 10ton, fin keeled 2-tonner, & the prop shaft exited the aft end of the keel's root about 12' in front of the rudder. So I had ZERO prop effect on the rudder. Which means the boat didn't respond to rudder input unless I was doing 2-3kts, be it in forward or reverse. And you have to "throw" & "catch" boats with such prop/rudder configurations.

That said, I had no issues with docking the boat, even in fierce Pacific Northwest conditions. As with that prop I had probably the best responsiveness to engine input, before or since. It stopped the boat with authority, & would also get her moving in either direction more quickly than most things I've driven (in terms of sailboats). Probably since Maxprop's have about as much pitch in reverse as they do in forward.

I'd have another one in a second, on anything that floats. Though, yes, there are other props which test slightly better. And the results of some of those tests can be found here on the forums. Plus, as noted by Ann, you'll sail a lot better.

Knock on wood, you shouldn't have much docking trouble with it. And you can change the pitch on them, some while on the shaft, in the water. So that it matches up with your boat & engine/transmission characteristics.
They also re-sell pretty well, should you want to find it a new home.

ErikFinn 20-08-2016 22:25

Re: 3 blade Max prop vs 3 blade fixed?
 
Quote:

Originally Posted by Davidhoy (Post 2193818)
The PO installed the fixed blade prop in place of the Max. He'd owned the boat just over two years, and I saw a copy of his pre-purchase survey that noted that the Max prop needed reconditioning. I suspect that he installed the fixed blade rather than do the reconditioning, probably due to cost.

I'm willing to recondition and reinstall the max prop if it will help with better handling when reversing. More power should make backing down easier, right? I don't really know the answer, hence my question...

Regards,
David


I reckon the biggest challenge with a Max Prop is to get the pitch settings correct. I have had two boats with a Max Prop and both had incorrect settings. I currently have a used Max Prop in my lazarette waiting for me to find out if I can use it on my current boat. You could contact the manufacturer PYI with your boat engine and transmission details and they should get back to you with recommended settings.

About the reconditioning, I didn't search the forum for answers but this is a good opportunity to bring this up: has anyone reconditioned a Max Prop by themselves? As DIY? I reckon it shouldn't be too difficult provided there is not too much structural damage.

Stumble 20-08-2016 23:45

Re: 3 blade Max prop vs 3 blade fixed?
 
A good feathering prop (MAX among them) is probably the best upgrade you can do for under power handeling. More thrust in reverse with less prop walk, and lower drag while sailing. While not cheap they are massive performance upgrades, probably second only to new sails in terms of performance gain under sailing as well.

MrSteve007 21-08-2016 02:07

Re: 3 blade Max prop vs 3 blade fixed?
 
On my Hunter 326 with an 18-hp Yanmar 2GM, I went from the stock fixed 2-blade to a 3-blade MaxProp. It was definitely one of the best upgrades I did for my boat. It bumped my cruising and max speeds up by about 1/2 a knot, both while under sail and under power (bringing down the fuel efficiency a bit). Before, due to the fin keel, prop walk was fairly notable. After the MaxProp, most all of the prop walk disappeared and backing/stopping power and performance dramatically improved.

Lastly, when plowing into heavy wind & seas, the three blade MaxProp has quite a bit more bite to maintain headway.

For me, it was worth every penny.



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jrbogie 21-08-2016 09:46

Re: 3 blade Max prop vs 3 blade fixed?
 
Quote:

Originally Posted by Davidhoy (Post 2193143)
I recently bought a Morgan 462, which are known for their horrendous handling when backing down. The boat has a 3 blade fixed prop installed, but I found a 3 blade Max prop in one of the storage compartments. It looks like it could use reconditioning, but otherwise seems ok. I did some reading, and Max props supposedly give you about 80% more power in reverse than a traditional fixed blade. If this is true, might switching to that prop help with my backing down handling issues? I'm not looking for a margin bullet that will suddenly make the boat a dream to handle in reverse, but rather something that will give me something, anything, better than what I have now with the fixed blade prop.

Regards,
David


Sent from my iPad using Cruisers Sailing Forum

prop walk is the problem when steering in reverse. as i see it anyway. my math says 80% more power in reverse equals 80% more prop walk in reverse resulting in 80% less steering control in reverse. i'm plagued with absolutely no ability to turn my bow to port with the prop producing ANY reverse thrust. feel free to check my math of course. i'm worse at math than i am at point my bow where i want to go in reverse.

skipgundlach 21-08-2016 10:04

Re: 3 blade Max prop vs 3 blade fixed?
 
Two things:

First, reconditioning can be very expensive, but it's worth it.

Second is that the shaft has to be cut appropriately; standard props have too much thread out (and may not be able to go back on because of not enough).

As to pitch, amen to that. David, I have a sistership and can give you our specs. skipgundlach@gmail.com far preferred for contact. The size of the prop will determine the right pitch; I'm assuming you have the original engine and tranny setup?

As to backing down, yes, indeed. All the thrust you would have had in forward.

As to backing, email me.

We sold our 3-blade spare which came with the boat; even if it meant replacement, we'd use the maxprop.

TacomaSailor 21-08-2016 10:11

Re: 3 blade Max prop vs 3 blade fixed?
 
There seems to be considerable mis-information in this thread.

I've had an 18" 3-blade Maxprop on our Caliber 40 since 1995.
We have put 2,850 engine hours on the prop. I've had the prop rebuilt the twice and changed the pitch three times.

1. I've done extensive testing of the prop under sail. I am certain that the prop feathering results in 0.4 to 0.6 knots increase in sailing speed compared to forcing it to stay full deployed. Those results have been obtained many times in winds from 6 knots apparent to 15-knots apparent on beats, reaches and runs.

2. The Maxprop innards are complicated and delicate. I sent the prop to PYI in Edmonds, WA after 2,000 hours to have them check everything and restore it to factory specifications. They found all the internal gears to be perfect. The blades needed a little fine tuning. At 2,700 hours I again had the gears checked and they were A-OK. However, the blades were pitted and eroded. A PYI approved shop in San Diego brought the blades back to as-new condition for $350.

3. Prop Walk in reverse is greatly enhanced by the MaxProp because pitch in reverse is the same as pitch in forward. That means the prop develops the same amount of thrust in reverse as forward.

4. Max Prop Walk is your friend almost all the time. You just have to plan your maneuvers to take advantage of the prop walk. I can spin Mirador 360 in about 5' more than it's length using the max prop walke.

5. It is very easy to set the pitch wrong. The internal gears are complicated and you need to be very careful when you install the prop. The first time we had the Maxprop installed resulted in a near disaster. The boat dealer installed the prop and got the pitch EXACTLY backwards. He tried to back away from the dock but the reverse lever caused the prop to go into forward and too much throttle caused the bow pulpit to strike the cribbing holding up the bow of a 50' powerboat that was towering above the dock. The boat swayed and wobbled but did not fall. Our bow pulpit was bent badly.

6. I would rank the addition of the Maxprop to our boat was the 2nd best addition, falling behind only the Raymarine autopilot.

7. I verified the thrust in Reverse by backing Mirador at 7.3 knots, just 0.2 knots slower than in Forward.

8. All that thrust in Reverse allows me to really set the anchor. My careful engineering calculations indicate that 3200 RPM in Reverse (Yanmar 4JH2E/50HP) puts the same load on the anchor as 35 knots wind from straight ahead. When I use 3000 RPM in reverse for 20-seconds and see no boat movement I know the anchor is down and digging and I sleep well at night.

Send your Maxprop to PYI and find out if it is good and then install it.

Chalifour 21-08-2016 10:39

Re: 3 blade Max prop vs 3 blade fixed?
 
Having sailed with both, Max prop over a fixed one is a no contest! Backing up is almost as efficient as forward and the propellor path is almost non existent. Why has the max prop not been installed is worth investigating. Good luck


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